Many motor homes, campers, and other recreational vehicles are equipped with toilets, showers, and sinks and, as a consequence, include within their systems holding tank facilities into which water and waste drain to be retained for later discharge into a sewer or other waste collection tank.
Holding tank facilities are typically provided with a discharge outlet and associated valve mechanism lowermost which are usually presented to the rear or to one side of the vehicle for ready attachment to one end of a suitable drainage hose or piping which can enter or be connected at its other end to a sewer inlet or other collection or storage tank located at the campground or mobile home site or at other designated locations in order to drain the vehicle holding tank and remain so connected for such purpose if vacationing or parked for an extended period of time.
The preferred drainage hose or piping is usually flexible or of light gauge and can be collapsible along its axis for ready storage, and of sufficient extended length to accommodate the drainage path or run leading from the vehicle holding tank discharge outlet to the sewer or collection or storage tank inlet.
The preferred drainage path or run extending from the vehicle holding tank to the sewer or collection or storage tank descends along a direct substantially uniform gradient so that an uninterrupted intermittent or continuous discharge of water and waste under gravity will be ensured. Consequently, it is important that any flexible or collapsible drainage hose be sufficiently supported over such a path so as to substantially maintain the required gradient.
Many proposals have been put forward which utilize intermittent or continuous ground engaging framework for supporting such flexible discharge hoses or piping, some including stiffened or extensible support segments or combinations thereof for establishing and maintaining the required flow gradient and orientation as revealed by the following U.S. Pat. Nos. 3,493,204, 3,572,622, 3,730,228, 3,809,348, 4,082,242, 4,194,711, 4,722,500, and 4,905,939.
It will be appreciated that any stiffened ground engaging framework will reflect the unevenness or contour of the location which would be imparted to the drainage hose and possibly interfere with or impede the flow rate, and, consequently, adjustments to the structure along the path would be required.
Further, some stiffened or extensible support segments of some proposals cannot readily accommodate changes in direction of the flexible discharge hose around obstacles such as bushes, trees, rocks, or the like, and will require still further adjustments or bending in order to properly orient the hose to establish and maintain the desired flow gradient.
An optimum gradient of the discharge flow path not only assists in ready continuous or intermittent drainage of the vehicle holding tank, but also facilitates thorough flushing out of the whole system including the flexible or collapsible hose itself which is especially important since the hose is to be stored in the vehicle and may remain in storage for lengthy periods.